I see two types. In the beginning, metalcore, as opposed to "crossover", was applied to early- 90's bands like Integrity, Biohazard, Earth Crisis...pretty much any of the Victory Records bands. Growing out of NYHC, that style was basically simplified speed metal riffs slowed down half-time and interspersed with breakdowns to mark the climax of a song. It grew in parallel to post-hardcore, and shares the same broad tendency to distance oneself from an ostensible punk sound while still carrying the same mentality. At some point, bands like Converge threw in emo and proggier tendencies to differentiate themselves from the more "toughguy" acts like Hatebreed.

What I think unites the two strands of metalcore, is a centering of songs not on distinct riffs so much as hooky percussive rhythmic arrangements wrapped in the dogmatic emotion of personality. It works well insomuch as you can throw any superficial style on top of it and make deathcore/mathcore/rapcore etc. Its all basically nu-metal with a crunchier guitar sound.

Having listened to two of their albums, I can hear good ideas, but they need to cut the fat and know when to conclude on a good heavy riff when they find one. There also needs to be better organization in the vocal phrasing and its placing within the song. Presentationwise, they're give off an overly tree-hugging mentality that doesn't really jive with the sound of black metal, atleast to my ears anyways.